There are numerous disclosures in the prior art of mechanisms for effecting the transfer of workpieces from one station in a multi-station forming die to the next successive station. For example, see U.S. Pat. No. 3,832,881 to Henzler and Spino. The essential motion required to effect the transfer of workpieces is rectilinear, namely, the workpiece must be lifted vertically from the station where an operation has just been performed on it, a sufficient distance to clear the forming die, then moved horizontally to a position overlying the next station in the forming die, then moved vertically downwardly into such next station, where it remains during the next stroke of the forming press. Obviously, the mechanism which translates the workpieces through such movements, has to be returned horizontally to its original position.
It follows, therefore, that every workpiece transfer mechanism requires some means for providing a horizontal reciprocating motion of the workpiece support frame with an equal dwell period at each extreme end of the horizontal motion. Prior arrangements for providing such motion have employed hydraulic cylinders and limit switches and have suffered the disadvantage of not being as accurate and trouble-free as desired. Furthermore, an elaborate and expensive hydro-electrical control system is necessitated to effect the desired horizontal reciprocating motion and the desired dwell periods at each of the extreme ends of the horizontal reciprocating motions.